Prior Laura, Oliveira Mónica S A, Zhiltsova Tatiana
Department of Mechanical Engineering, Centre for Mechanical Technology and Automation (TEMA), University of Aveiro, 3810-193 Aveiro, Portugal.
LASI-Intelligent Systems Associate Laboratory, 4800-058 Guimaraes, Portugal.
Materials (Basel). 2023 Jan 31;16(3):1198. doi: 10.3390/ma16031198.
Single-use plastics are a matter of convenience in everyday life, with the majority allocated to packaging production. However, it comes with a high environmental price as its mass recycling is challenging due to the heterogeneity of composition, contaminations of different kinds, and degradation caused by service and processing. This study aims to ascertain the impact of removing contaminants from post-consumer recycled polypropylene (rPP) on its degradation and properties by implementing a systematic approach for decontamination by washing. Four lots of recycled plastics with different degrees of contamination were evaluated via Fourier transform infrared, melt flow indexer, and differential scanning calorimetry and tested for tensile strength. Degradation of the rPP was manifested by the deterioration in ductility, resulting in 14.58% elongation at break (unwashed rPP) compared with 191.41% (virgin PP)) and a significant reduction in oxidation induction time. In the unwashed rPP sample, a wave intensity peak at 1730 cm, assigned to the saturated C = 0 stretch of the carbonyl functional group, was detected. This peak was gradually disappearing with an increase in the cleaning efficiency of rPP, highlighting the role of contaminants as degradation catalysts. The cold-washing method showed similar processing and mechanical performance improvement results compared with the other washing methods, while being more environmentally friendly and energy efficient.
一次性塑料在日常生活中提供了便利，其中大部分用于包装生产。然而，它带来了高昂的环境代价，因为其大规模回收具有挑战性，这是由于成分的异质性、各种污染以及使用和加工过程中造成的降解。本研究旨在通过实施一种系统的洗涤去污方法，确定从消费后回收聚丙烯（rPP）中去除污染物对其降解和性能的影响。通过傅里叶变换红外光谱、熔体流动指数仪和差示扫描量热法对四批不同污染程度的回收塑料进行了评估，并测试了拉伸强度。rPP的降解表现为延展性下降，与原始聚丙烯（191.41%）相比，未洗涤的rPP的断裂伸长率为14.58%，氧化诱导时间显著缩短。在未洗涤的rPP样品中，检测到在1730 cm处有一个波强度峰，该峰归属于羰基官能团的饱和C = 0伸缩振动。随着rPP清洗效率的提高，这个峰逐渐消失，突出了污染物作为降解催化剂的作用。与其他洗涤方法相比，冷洗方法在加工和机械性能改善方面显示出类似的结果，同时更环保且节能。
